Control for refrigerating systems



June 2, 1942. A. B. NEWTON 2,284,918

CONTROL F OR REFRIGERATING SYSTEMS Filed July 12, 1940 INVENTQR Alwin. B. Nzwi'om ATTORNEY Patented June 2,1942

' UNITED STAT coN'raoLr-oa nErnIGEaA'r NG SYSTEMS .Alwin B. Newton, Minneapolis," Minn, assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application July 12,1940, Serial, lfl'or 345,252

. I a 21 claim. (01. 62-4) My invention relates to the art of refrigeration dealing-more particularly with refrigerating apparatus of the compression type and automatic control therefor.

' s The primary object ofmy intention is to provide an automatic controller for refrigeratingapparatus of the compressiontype such that whenever the compressor is stopped the evaporator temperature'w'ill rise to a value assuring that the evaporator becomes defrosted before the compressor can again be restarted.

Another object of my invention is to provide a suction pressure controller for compression type refrigerating apparatus in the form of a suction pressure responsive switch which is vopened in response to the rise in suction pressure whenever the compressor is stopped by any automatic con-. trol device or other agency.- 1

Another object is toprovide a suction pressure controller in the form of a switch for starting the compressor at a predetermined high suction v pressure-and for stopping it at a predetermined relatively low suction pressure and having means for. opening the switch in response to the rise in suction pressure whenever the compressor is stopped when the suction pressure responsive switch is still in closed position.

Another object is to provide a suction pressure responsive switch for controlling a compressor which starts the compressor at a predetermined "relatively'highsuction pressure and stops it at a predetermined relatively low pressure and having a device responsive to compressor discharge pressure which may move the switch to open position so that the suction pressuremust again rise to the predetermined relatively high value before it can be closed again.

Another object of my invention is to provide a switching mechanism embodying a switch-operable betweenon and off positions by an operating member movable between corresponding positions and having a yieldable connection between the operating member and the switch whereby the operating member. may operate the switch at a point between said positions if the operating member moves 'in a direction to operate the switch to a given position wjhenthe switchis already in that position. 7

' the invention'is' to provide a switching mechanism embodying a switch oper- Another object of member may move the switch to one position when the operating member'is moving in a direction to normally move the switch to the opposite position,

3 5 Another object of the invention is to provide aswitching mechanism embodying a switch operable between closed and open positions by a member movable between corresponding positions and having a yieldable'connection comprising a pivoted arm 'actuatable by the operating member whereby the switch may be operated to one posi-. tion when the operating member is movinggin a directiontonormally operate the switch to the other position. a 1

Another object of the invention is to provide in a switching mechanism a switch operable by a member movable between given positions and Y having a yieldable connection embodying a ratchet and a resilient pawl between the operating member and the switch so arranged; that the operating member mayopen the switch when it is moving in a direction to normally close it. 4

For a better understanding of my invention reference may be had to the following detailed description and annexed drawing wherein the single figure represents an embodiment of my improved controller in combination with a compression type refrigerating system.

Referringftothe drawing, .numeral l0 designates generally a refrigerating system of the compression type. -'The system comprises a compressor II,. a condenser and an expander 10- catedwithin a space or chamber l3 to be refrigated, the compressor, condenser and expander 'being connected in the usual circuit relationship by pipes [4,. l5, and I6 whereby refrigerant may. be translated from the compressor to the condenser and the expander. An expansion valve iii of any well known type may be interposed in the pipe I 5 connected between the condenser and expander. The compressor II is driven by an *Jle between open and closed positions'by a a member movable between coresponding positions nd a one way y1eldable connection between the operating member and the vswitch whereby through the yieldable connection the operating electric motor 9 through'a belt H.

For controlling the compressor I have provided a controller which is primarily responsive to suction pressure and which is designated generally cury switch 24, the mercury switch being mount- I ed in a suitable clip. The lever 22 is movable between fixed stops l9. and 29. v The lower end of the lever 22 is shaped in the form of a yoke having downwardly extending arms 25 and 28.

the numeral 20; The controller is housed in a casing designated by the broken lines and in- ,cludes pressor suction pipe l6 by a tube. 42.

a pin 3| is an arm 32 the upper end of which bears against the screw 21. Numeral 33 designates a similar disc adjustable from outside the casing and to which is eccentrically pivoted an arm 34, the arm 34 being pivoted on a pin 35 carried by the disc 33.

both the arms 32 and 34 are normally urged away from each other and into engagement with their respective screws by a coil spring 35. Numeral 39designates a lever arm pivoted on a pin 40 at the lower part of the casing, the upper part oil-the arm being disposed between the arms 32 and 34. The upper end of the arm 39 has adapted to engage the small lateral extensions arms 32 and 3.4.

Numeral 4| designates an expansible and contractible bellows element connected to the com- The movable end oi'the bellows 4| carries a stem 43 at The upper endof arm. 34 bears against screw 28 and the upper ends of 9 a volatile liquid 'so that the bellows expands and contracts in accordance with the temperature aflecting the bulb 12. The movable end of the bellows II carries a stem 14 which actuates a pivoted lever 15 carrying a mercury switch 16,

' the'lever l5being biased against the stem 14 by a spring TI.

the end of which is formed a'knife edge engaged in a suitable notch near the lower end of the arm 39 whereby the 'pressure'exerted by the bellows 4| urges the arm 39 in a counter-clockwise direction. The bellows 4| of course expands and contractsin accordance with the suction pressure existing in pipe l6. Numeral 4t designates a coil spring, one end of which is connected to the arm 39 and the other end at which is attached to an element 45 in screw threaded engagement with which is a screw 46 extending through a side wall of the casing whereby the 1 screw may be adjusted from outside the casing so as to adjust the tension of. spring 44. The spring 44 urges the, arm 39 in a clockwise direction against the stem 43.

Numeral 50'designates a lever pivoted on a fixed pivot 5| and having a horizontal portion 52 adapted to bearagainst the arm 25 of lever 22. Numeral 53 designates a coil spring one end of which is attached to the pivot pin 5| and the other end of which engages the lever 50 so as to urge it in a counter-clockwise direction. Piv-'.

oted to the lower end of the lever 50 is an arm 54, the opposite end of which is disposed above the-upper end of the arm 39, its lower edge hav- When the temperature affecting the bulb I2 rises to-a predetermined value the bellows expands sufficiently to tilt the lever 15 in a counter-clockwise direction until the mercury switch 16 is closed, its electrodes being at its left end as shown.

' When both the mercury switches 24 and T6 are ,closed the compressor motor 9 may be energized through a circuit as follows: wire 19, mercury switch 24, wire 60, mercury switch 16, wire 6|, and

the compressor motor 9 to wire 82, the wires I9 and 82 being connected to any suit-able source of power not shown. With the parts in the position shown the compressor has been in operation and has been stopped 1 by reason of the temperature within the refrigerated space falling to a low enough value to cause opening of the mercury switch 16. The suction pressure was at an intermediate value when the compressor was stopped,

so that the arm 39 has assumed a position-intenthe left rotating lever 50 in a clockwise direction as soon as the suction pressure starts rising. The portion 52 of lever 50 now will bear against arm 25 of lever 22 rotating the lever 22 ina ing teeth formed therein so as to form a ratchet 55. Theupper end of the arm 39 carries a resilient leai or reed 56 which is adapted to engage urges the lever 63 in a counter-clockwise direction and the lever 631s biased in a clockwise direction into engagement with the stem 62 by a coil spring 66 one end of which is attached to the lever and the other end of which is attached to a'memberj6l, in screw threaded engagement with which is a screw 66 extending through a sidewall of the casing. The screw 66 may be adjusted'from outside the casing for varying the tension of spring 66. The-transverse portion 64 of lever 63 extends to a point adjacent the upper part of lever 22 and as will presently be pointed pounds for example, the pawl 56 bears against a counter-clockwise direction until it engages the stop l9 thereby tilting the mercury switch 24 into open position. After lever 22 has thus engaged the stop l9 its further rotation will be prevented and thus rotation of lever 50in a clockwise direction by movement of the arm 54 to the left will be prevented. However, the suction pressure will continue to rise causing lever 39 to continue to move in a counter-clockwise direction, and due to its resiliency the pawl 56 will override the ratchet as the arm 39 continues itsleftward movement. The extent of the ratchet teeth 55 is such that after the suction pressure has risen to a value which may be 25 or 35 smooth part of arm 54 so as not to be retarded.

The. teeth 55 are of such size that minor risesof suction pressure of five pounds or less will not operate the switch. When the suction pressure has risen to apredetermined relatively high value at whichthe, evaporator l3 will have been defrosted, the upper'end of arm 39 will engage the arm 32 movingthe arm 32 in acounterclockwise-direction so thatits upper end bearing against the screw 21 will move the lever 22 in a clockwise direction-until it engages the stop 20 with the mercury switch 24 closed (as seen out may engage the lever 22 for operating the in a position wherein the compressor can be started whenever there is a demand from the thermostatic device 10, the position or the parts response to a further 'rise in suc-- Whenever the temperature in bulb l2 risestola predetermined value causin not changing in tlon pressure.

on the drawing);- The controller 20 will now be.

;-com'e defrosted before the compressor can be restarted. -My improved controller. is mechanical in its operation and is of a very inexpensive closure of mercury switch 16 the above described circuit for the compressor motor I6 is completed.

'Aslsoon as the compressor starts the suction pressure begins to fall thereby causing bellows 4| to contractand permitting movement of arm 39 in a clockwise direction, that is, to the right.

The upper end of' arm 39 will'now move away from arm 32 without of the controller and when the suotioii 1 changing the position of the parts pressure has fallen to a predetermined relativee .ly low value if the compressor has not-been 7 I claims.

stopped by the thermostatic'device III the upper 3' .end 0t arm 39 will come into engagement with arm 34'. As the suction pressure decreases arm 39 will move arm 34 in a clockwise direction,

that is, to the right so that its upper end bearing againstscrew 29 will rotate lever 22 in a counter-clockwise direction until it engages stop l9 with the mercury switch 24 in an open position. Mercury switch 24 being thus opened the motor IE will be deenergized thus sto'pping'the compressor.

From the foregoing it will be seen that as long as the thermostatic device .-is calling for refrigeration the compressor will beoperated be- ,tween high an low limits of suction pressure.

If thecompressor is stopped by the thermostatic device when the suction pressure is at an intermediate value, then the mercury switch 24 will be opened by the ensuing rise insuction pressure and the suction pressure must then rise to apredetermined relatively high value before the mercury switch 24 will againbe closed to permit restarting of the compressor. The suction pressure valuetat which the mercury switch 24 is closed is set) high enough to insure that after each cycle of the compressor, 'the'pressure within the evaporator will rise to a high enough valus. to insure that it becomes defrosted.

In the event that the compressor discharge pressure, that is, the head pressure.should rise to an unduly high value the bellows 60 will be expanded moving lever '63 in-a counter-clockwise, direction until the portion 64 engages the. lever 22 and rotates it about'its pivot against the stop vl9 thus opening the mercury switch 24.

Thus the compressor may be stopped by reason of the head pressure rising toan unduly high valueand compressor operation will be prevented as long as the head pressureis ata high enough value to maintain the lever 22 against the stop l9 with mercury switch 24 in the open position.

If the mercury switch 24 has been opened by reason'of the head pressure rising toan unduly high value the compressor can of course not be restarted until the-suction pressure rises to a high enough value to cause defrosting of the evaporator at which the arm :9 acts to brin about closure of mercury switch as above der .scribed. When the head pressure drops the bellows 60 contracts moving the portion 64 of lever 63 away from lever 22 and leaving the lever 22 in the position to which it was moved.

type of construction not employing delicate or uncertain mechanisms 1 The single embodiment of my invention which I have disclosed is representative of its preferred form'and application although it maytake various other forms and numerous modifications may I be made of it, wherefore my invention is not to be limited by my disclosure which is illustrated in accordance with the "scope I-claim as my invention:

increased and decreased, a device arranged to cause saidforce to vary, said switch mechanism controlling the operation of said device, the force varying in one direction when the device is in operation and in the opposite direction when the. device is not in operation, said switch mechanism being arranged to start the device when the force is atone value and tostop the device at a relatively different value of the force, additional automatic .means for stopping the device, and means for operating said switching mechanism to stopping position in response to the change in force in said opposite direction resulting from stopping of the device by said automatic means.

2. In a reirigeratingsy'stem having a com- ,pressor, a condenser, and an expander, means responsive to. compressor suction pressure con-.

stopping oi the compressor by said automatic device.

3. Inarefrigerating system having a compressor, a condenser, .and an expander, means responsive to compressor suction pressure controlling the compressor, said means including a v switch and operating means therefor whereby the switch is operated at a predetermined relatively high suction pressure to start the compressor and at a predetermined low suction pressure to stop the compressor, an additional automatic device for stopping-the compressor, means for operating said switch to stopping position in response to the resulting rise in suction pressure when the compressor is stopped by said automatic device,

and means responsive to compressor ,discharge" pressure for also operating said switch'to stop-- ping position. I

4. In a refrigerating system having a compressor, a condenser, and an expander, means responsive to compressor suction pressure controlling the compressor, said means including a From the foregoing those skilled in the art I will appreciate that I have provided a very use- 'ful and practical arrangement for controlling the compressor of a refrigerating system in such a manner that whenever the compressor is switch and operating means therefor whereby the switch is operated at a predetermined relatively high suction pressure to start the compressor and at a .predeterintned low suction pressure to stop the compressor, an additional automatic device for stopping the compressor, and means for operating said switch to stopping position in'respoiise to therise in suction pressure which occurs when the compressor is-stopped by said automatic. de-

stopped for any reason the evaporator will-be.

of the. appended 1. In apparatus of the character described, in combination, switch mechanism, means for pro-' 'ducing a switch actuating force adapted to be vice, said next to last mentioned means comprising a yielding one way connection between said suction pressure responsive means and switch.

5. In a refrigerating system having a compressor, a condenser, and an expander, means responsive to compressor suction pressure controlling the compressor, said means including a switch and operating means therefor whereby the switch is operated at a predetermined relatively high suction pressure to start the compressor and at a predetermined'low suction pressure to stop the compressor, an additional automatic device for stopping the compressor, and means forming part of said suction pressure responsive means for-operating said switch to stopping position in response to the rise in suction pressure which occurs when -the compressor .is stopped by said automatic device, said next to last mentioned means comprising a pawl and ratchet mechanism, said pawl being yieldable whereby after moving said ratchet to open said switch, the pawl overrides the ratchet teeth.

6. In a refrigerating system having acompressor, a condenser, and an expander, means responsive to compressorsuction pressure controlling the compressor, said means including a switch and operating means therefor whereby the switch-is operated at a'predetermined relatively high suction pressure to start the compressor and at a predetermined low suction pressure to stop the compressor, an additional automatic device forstopping the compressor, means for operating said switch to stopping position in response to the rise in suction pressure which occurs when the compressor is stopped by said automaticdevice, said operating means comprising a first switch actuating arm, a second pivoted switch actuating arm, said second arm coacting with said first arm whereby movement of a part of saidsecond arm in one direction moves the first arm in the opposite direction, an actuator for said arms, and means forming a yielding connection between said actuator and one of said arms whereby said actuator can move said one arm to operate the switch to stopping position, the yielding connection permitting continued movement of the actuator in the same direction whereby it can actuate the other arm to operate the switch to starting position.

7. In a refrigerating system having a compressor, a condenser, and an expander, means responsive to compressor suction pressure controlling the compressor, said means including a switch and operating means therefor whereby the switch is operated at a predetermined relatively high pressure to start'the compressor and at a predetermined low pressure to stop 'the compressor, an additional automatic device for stopping the compressor, means for operating said switch to starting position in response to the rise in suction pressure which occurs whenthe compressor is stopped by said automatic device, said operating means comprising a first switch actu-' ating arm, a second pivoted switch actuating arm, said second arm coacting with said first arm whereby movement of a part of said second arm in one direction moves the first arm in the opposite direction, an actuator for said arms, and

position, said connection comprising a ratchet and a pawl adapted to override the ratchet teeth when the ratchet resists movement by the pawl.

8. In a' refrigerating system having a compressor, a condenser, and an expander, means responsive to compressor suction pressure controlling the compressor, said means including a switch, a switch carrying element, stops between which said element moves, and a membermovable between predetermined limits for engaging and actuating said element whereby said switch starts the compressor at a predetermined relatively high pressure and stops the compressor at a predetermined low pressure, an additional automatic device operable to stop the compressor,

and means forming a yielding one way conneotion between said member and element whereby said member can move said element in one direction at any point between the limits of movement of said member if said element is not restrained from being moved by one of said stops,

- said releasable connection permitting movement of said member when said element is so restrained.

9. Inapparatus combination, a switch having on and off positions, switch operating means responsive to pressure changes whereby the switchis operated to one position upon a rise in pressure and to another position upon a fall in pressure, and means whereby if there is arise in said pressure when said switch is in said one position said operating means operates said switch to said other position.

10. In apparatus of the character described, in combination, a switch having on and oii positions, switch operating means responsive to pressure'ch'anges whereby the switch is operated to one position upon a rise in pressure through a given range and to another position upon a fall in pressure through said range, and means whereby if the said pressure reverses its direction of'change at an intermediate point in its range and changes a given amount the switch is op erated to its opposite position.

11. In apparatus of the character described, in combination, a switch having on and oil positions, switch operating means responsive to pressure changes whereby the switch is operated to one position upon a rise in pressure through a given range and to another position upon a fall in said pressure through said range, and means whereby if the pressure reverses its direction of change at an intermediate point inv its range the switch is operated to its opposite position, said, last means comprising a pawl and ratchet mechanismythe ratchet being movable by the pressure responsive means in one direction for' operating the switch.

12. In apparatus of the character described, in combination, a switch having on and ofi positions, switch operating means responsive to pres: sure changes whereby the switch is operated to one position upon a rise in pressure through a given range and to another position upon a fall in pressure through said range, and means whereby if the said pressure reverses its direction of change at an intermediate point in its range the switch is operated to its opposite position, said last means comprising a pawl and ratchet mechanism, the ratchet being movable by the pressure responsive means in one direction for operating the switch, said pawl being resilient whereby it may override the ratchet teeth.

' 13. In apparatus of the character described, in

of the character described, in-

combination, a switch having on and off positions, switch operating means responsive tov pressure changes whereby the switch is operated to one position upon a rise in pressure to a given value and to another position upon a fall in pressure to a given value, and means whereby said switch is operated to said other position upon rise in said pressure when said switch is in said one position.

14. In apparatus of the character'described, in combinatioma switch, force producing means for operating the switch whereby it has a given differential, and means forming an operative connection between the operating meansand switch whereby if the ,force changes within said differential in a direction to normally move the switch to one position when the switch is already in that position, the switch will be moved to the opposite position.

15. In apparatus of the character described, in combination, a switch, an opera ing member for the switch for operating the switch between comprising a pivoted arm, said arm being yieldably engaged with said member and said arm being so related to the switch so that when the switch is operated through the arm it is operated Y to a position opposite to that it would normally be operated to by movement of the member in the same direction. 4

18. In apparatus of the character described in combination, a switch, a switch carrying element, a stop cooperating with said element, a member movable between predetermined limits for engaging and actuating said element to operate the switch, and means embodying a yielding connection between said member and element whereby said member can move said element at any point between the limits of movement of said member if said element is not restrained by said stop, said yielding connection permitting movement of said member if said element isso restrained.

19. In apparatus of the character described in combination, a switch, a first switch actuating arm, a second pivoted switch actuating arm, said second arm coacting with said first armwhere- 16. In apparatus of the character described, in

combination, a switch, an operating member for the switch for operating the switch between on and ofi positions as the member moves between corresponding positions, and means forming a yielding connection between said member and switch whereby if said member moves in a direction to normally move said switch to a given position when it is already in that position said connecting means operates to move said switch tothe opposite position, said yielding connection permitting continued movement of said member in said direction, said yielding connection comprising a pawland ratchet mechanism, the pawl being yieldable so as to override the ratchet teeth.

17. In apparatus of the character described, in combination, a switch, an operating member for the switch for operating the switch between on and off positions as themember moves between corresponding positions, and means forming a yielding connection between said member and switch whereby if said member moves in a direction to normally move said switch to a given position when it is already in that position said connecting means operates to move said switch to the opposite position, said yielding connection permitting continued movement of said member in said direction, said connection means said arms, and means forming a yielding ccn-- by movement of a part of' said second arm in one direction moves the first arm in the opposite direction, a switch operator for actuating said arms, and means forming a yielding connection between said operator and one of said arms whereby said operator can move said one arm to operate the switch to a given position, the

' yielding connection permitting continued movement of the operator in the same direction whereby it can actuate the other arm to operate the'switch to the opposite position.

20. In apparatus of the character described in combination, a switch, a first switch actuating arm, a second pivoted switch actuating arm,

.said second arm coacting with said first arm whereby movement of apart of said second arm in one direction moves the first arm in the opposite direction, a switch operator for actuating nection between said operator and one of said arms whereby said operator can-move said one arm to operate the switch to a given position, the yielding connection permitting continued movement of the operator in the same direction whereby it can actuate the other arm to operate the switch to the opposite position, said connection comprising a ratchet and a pawl adapted to override the ratchet teeth whenthe ratchet resists movement by the pawl.

21. In a refrigerating system, a switch in circuit with a refrigerant compressor, suction pressure responsive means i'oractuating the switch adapted to close the switch on a-pressure rise and open it on a pressure fall, and means adapted to open the switch onv a pressure rise when'the switch is closed.

ALWIN B. NEWTON. 

